Light, chromatin and alternative splicing

MICAELA A. GODOY HERZ; EZEQUIEL PETRILLO; ALBERTO KORNBLIHTT

Congreso; 11th International Congress of Plant Molecular Biology; 2015

Light is not only a source of energy but also a key regulator of plant physiological adaptations. We have previously shown that light/dark conditions affect several alternative splicing events including that of the Ser-Arg-rich splicing factor RS31. This led us to investigate whether chromatin modifications play a role in the regulation of alternative splicing by light. Increasing concentrations of trichostatin A (TSA), a drug that suppresses histone deacetylase activity and therefore increases histone acetylation, mimic the effect of light on At-RS31 alternative splicing in a dose-dependent manner. The light/dark effect and the TSA effect on alternative splicing are not observed in the pre-mRNA for At-RS2Z33, another SR-splicing factor used as a control. Global histone acetylation does not change between light and dark treated plants. Using Arabidopsis mutants defective in different histone modifying enzymes we found that the effect of light to dark transition on alternative splicing is strongly reduced in mutants that show higher levels of histone acetylation, such as the histone deacetylase hd1 or the histone methyltransferase kyp6. This isconsistent with the TSA treatment. In contrast, an Arabidopsis mutant defective in a histone acetyltransferase, taf1, shows a stronger light to dark transition on alternative splicing compared to wild type plants. We are currently performing chromatin immunoprecipitation experiments to study changes in specific chromatin marks such as H3K9 acetylation and dimethylation to determine the link between chromatin modifications and alternative splicing regulation by light.